PROJECT SUMMARY Suicide is the 10th leading cause of death among all U.S. citizens and is the 2nd leading cause of death among youth and emerging adults between the ages of 15 and 29. One group that is particularly vulnerable to suicide is sexual and gender minorities (SGMs). SGM is an umbrella term used to describe individuals who identify as non-exclusively heterosexual (e.g., gay, lesbian, bisexual) and/or as transgender/non-binary (e.g., identify as a gender different from their birth sex). Indeed, recent U.S. representative findings from 2017 underscore striking disparities in suicidality between sexual minority and heterosexual adolescents, with 23% of sexual minority youth reporting one or more suicide attempts (in the past 12 months) vs. 5.4% of heterosexual youth. Prevalence of lifetime suicide attempts among gender minorities is also substantially elevated compared to the general population, with 45% of 18-24-year-old transgender individuals reporting a history of one more suicide attempts. Despite these substantial health disparities in suicide among SGM youth/emerging adults, no known suicide prevention programs exist for this highly vulnerable population. Given this crucial gap in the literature, the proposed study will adapt and test an innovative intervention that integrates patient navigation with the Safety Planning Intervention (PN+SPI) for SGM youth/emerging adults designed to target mechanisms (e.g., reductions in thwarted belongingness and increases in suicide-related coping skills) that theoretically underlie suicide. If the PN+SPI intervention displays a clinically meaningful effect on the purported targets (i.e., reductions in thwarted belongingness and increases in suicide-related coping skills) during the open-phase trial (R61 phase) and is feasible and acceptable, we will subsequently move to the R33 phase. In the R33 phase, we will conduct a pilot randomized controlled trial of the PN+SPI by comparing it to SPI alone to assess feasibility, acceptability, and preliminary efficacy. During the randomized controlled trial, in which we will sample 170 youth and emerging adult SGMs, we will also evaluate the mechanisms of action of the PN+SPI intervention through longitudinal analysis. The proposed project has substantial public health significance as SGMs are one of the most vulnerable groups for suicidality globally. Given the brevity of the PN+SPI intervention and its emphasis on safety planning and accessing community resources, the PN+SPI intervention has high potential for wide dissemination and public health impact.